Answer :
It's the Helium.
The Electron configuration of the Oxygen is [tex]1s^2 2s^2 2p^4[/tex]
And the Helium is represented by the [tex]1s^2[/tex]
So, the [tex]1s^2[/tex] of the oxygen can be replaced by Helium
Hope this Helps :)
The Electron configuration of the Oxygen is [tex]1s^2 2s^2 2p^4[/tex]
And the Helium is represented by the [tex]1s^2[/tex]
So, the [tex]1s^2[/tex] of the oxygen can be replaced by Helium
Hope this Helps :)